Publications by authors named "Ann J Hessell"

48 Publications

Modified Adenovirus Prime-Protein Boost Clade C HIV Vaccine Strategy Results in Reduced Viral DNA in Blood and Tissues Following Tier 2 SHIV Challenge.

Front Immunol 2020 15;11:626464. Epub 2021 Feb 15.

Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, United States.

Designing immunogens and improving delivery methods eliciting protective immunity is a paramount goal of HIV vaccine development. A comparative vaccine challenge study was performed in rhesus macaques using clade C HIV Envelope (Env) and SIV Gag antigens. One group was vaccinated using co-immunization with DNA Gag and Env expression plasmids cloned from a single timepoint and trimeric Env gp140 glycoprotein from one of these clones (DNA+Protein). The other group was a prime-boost regimen composed of two replicating simian (SAd7) adenovirus-vectored vaccines expressing Gag and one Env clone from the same timepoint as the DNA+Protein group paired with the same Env gp140 trimer (SAd7+Protein). The env genes were isolated from a single pre-peak neutralization timepoint approximately 1 year post infection in CAP257, an individual with a high degree of neutralization breadth. Both DNA+Protein and SAd7+Protein vaccine strategies elicited significant Env-specific T cell responses, lesser Gag-specific responses, and moderate frequencies of Env-specific T cells. Both vaccine modalities readily elicited systemic and mucosal Env-specific IgG but not IgA. There was a higher frequency and magnitude of ADCC activity in the SAd7+Protein than the DNA+Protein arm. All macaques developed moderate Tier 1 heterologous neutralizing antibodies, while neutralization of Tier 1B or Tier 2 viruses was sporadic and found primarily in macaques in the SAd7+Protein group. Neither vaccine approach provided significant protection from viral acquisition against repeated titered mucosal challenges with a heterologous Tier 2 clade C SHIV. However, lymphoid and gut tissues collected at necropsy showed that animals in both vaccine groups each had significantly lower copies of viral DNA in individual tissues compared to levels in controls. In the SAd7+Protein-vaccinated macaques, total and peak PBMC viral DNA were significantly lower compared with controls. Taken together, this heterologous Tier 2 SHIV challenge study shows that combination vaccination with SAd7+Protein was superior to combination DNA+Protein in reducing viral seeding in tissues in the absence of protection from infection, thus emphasizing the priming role of replication-competent SAd7 vector. Despite the absence of correlates of protection, because antibody responses were significantly higher in this vaccine group, we hypothesize that vaccine-elicited antibodies contribute to limiting tissue viral seeding.
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http://dx.doi.org/10.3389/fimmu.2020.626464DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7917243PMC
February 2021

Virus Control in Vaccinated Rhesus Macaques Is Associated with Neutralizing and Capturing Antibodies against the SHIV Challenge Virus but Not with V1V2 Vaccine-Induced Anti-V2 Antibodies Alone.

J Immunol 2021 Feb 3. Epub 2021 Feb 3.

Department of Pathology, New York University School of Medicine, New York, NY 10016;

The role of vaccine-induced anti-V2 Abs was tested in three protection experiments in rhesus macaques. In an experiment using immunogens similar to those in the RV144 vaccine trial (Anti-envelope [Env]), nine rhesus macaques were coimmunized with gp160 DNA and SIV gag and gp120 and gp120 proteins. In two V2-focused experiments (Anti-V2 and Anti-V2 Mucosal), nine macaques in each group were immunized with V1V2 DNA, V1V2 and V1V2 proteins, and cyclic V2 peptide. DNA and protein immunogens, formulated in Adjuplex, were given at 0, 4, 12, and 20 weeks, followed by intrarectal SHIV challenges. Peak plasma viral loads (PVL) of 10-10 copies/ml developed in all nine sham controls. Overall, PVL was undetectable in one third of immunized macaques, and two animals tightly controlled the virus with the Anti-V2 Mucosal vaccine strategy. In the Anti-Env study, Abs that captured or neutralized SHIV inversely correlated with PVL. Conversely, no correlation with PVL was found in the Anti-V2 experiments with nonneutralizing plasma Abs that only captured virus weakly. Titers of Abs against eight V1V2 scaffolds and cyclic V2 peptides were comparable between controllers and noncontrollers as were Ab-dependent cellular cytotoxicity and Ab-dependent cell-mediated virus inhibition activities against SHIV-infected target cells and phagocytosis of gp120-coated beads. The Anti-Env experiment supports the role of vaccine-elicited neutralizing and nonneutralizing Abs in control of PVL. However, the two V2-focused experiments did not support a role for nonneutralizing V2 Abs alone in controlling PVL, as neither Ab-dependent cellular cytotoxicity, Ab-dependent cell-mediated virus inhibition, nor phagocytosis correlated inversely with heterologous SHIV infection.
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http://dx.doi.org/10.4049/jimmunol.2001010DOI Listing
February 2021

Polyfunctional Tier 2-Neutralizing Antibodies Cloned following HIV-1 Env Macaque Immunization Mirror Native Antibodies in a Human Donor.

J Immunol 2021 Mar 20;206(5):999-1012. Epub 2021 Jan 20.

Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006;

Vaccine efforts to combat HIV are challenged by the global diversity of viral strains and shielding of neutralization epitopes on the viral envelope glycoprotein trimer. Even so, the isolation of broadly neutralizing Abs from infected individuals suggests the potential for eliciting protective Abs through vaccination. This study reports a panel of 58 mAbs cloned from a rhesus macaque () immunized with envelope glycoprotein immunogens curated from an HIV-1 clade C-infected volunteer. Twenty mAbs showed neutralizing activity, and the strongest neutralizer displayed 92% breadth with a median IC of 1.35 μg/ml against a 13-virus panel. Neutralizing mAbs predominantly targeted linear epitopes in the V3 region in the cradle orientation (V3C) with others targeting the V3 ladle orientation (V3L), the CD4 binding site (CD4bs), C1, C4, or gp41. Nonneutralizing mAbs bound C1, C5, or undetermined conformational epitopes. Neutralization potency strongly correlated with the magnitude of binding to infected primary macaque splenocytes and to the level of Ab-dependent cellular cytotoxicity, but did not predict the degree of Ab-dependent cellular phagocytosis. Using an individualized germline gene database, mAbs were traced to 23 of 72 functional IgHV alleles. Neutralizing V3C Abs displayed minimal nucleotide somatic hypermutation in the H chain V region (3.77%), indicating that relatively little affinity maturation was needed to achieve in-clade neutralization breadth. Overall, this study underscores the polyfunctional nature of vaccine-elicited tier 2-neutralizing V3 Abs and demonstrates partial reproduction of the human donor's humoral immune response through nonhuman primate vaccination.
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http://dx.doi.org/10.4049/jimmunol.2001082DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7887735PMC
March 2021

Efficacy of silk fibroin biomaterial vehicle for in vivo mucosal delivery of Griffithsin and protection against HIV and SHIV infection ex vivo.

J Int AIDS Soc 2020 10;23(10):e25628

Department of Medical Microbiology & Immunology, School of Medicine, University of California Davis, Davis, CA, USA.

Introduction: The majority of new HIV infections occur through mucosal transmission. The availability of readily applicable and accessible platforms for anti-retroviral (ARV) delivery is critical for the prevention of HIV acquisition through sexual transmission in both women and men. There is a compelling need for developing new topical delivery systems that have advantages over the pills, gels and rings, which currently fail to guarantee protection against mucosal viral transmission in vulnerable populations due to lack of user compliance. The silk fibroin (SF) platform offers another option that may be better suited to individual circumstances and preferences to increase efficacy through user compliance. The objective of this study was to test safety and efficacy of SF for anti-HIV drug delivery to mucosal sites and for viral prevention.

Methods: We formulated a potent HIV inhibitor Griffithsin (Grft) in a mucoadhesive silk fibroin (SF) drug delivery platform and tested the application in a non-human primate model in vivo and a pre-clinical human cervical and colorectal tissue explant model. Both vaginal and rectal compartments were assessed in rhesus macaques (Mucaca mulatta) that received SF (n = 4), no SF (n = 7) and SF-Grft (n = 11). In this study, we evaluated the composition of local microbiota, inflammatory cytokine production, histopathological changes in the vaginal and rectal compartments and mucosal protection after ex vivo SHIV challenge.

Results: Effective Grft release and retention in mucosal tissues from the SF-Grft platform resulted in protection against HIV in human cervical and colorectal tissue as well as against SHIV challenge in both rhesus macaque vaginal and rectal tissues. Mucoadhesion of SF-Grft inserts did not cause any inflammatory responses or changes in local microbiota.

Conclusions: We demonstrated that in vivo delivery of SF-Grft in rhesus macaques fully protects against SHIV challenge ex vivo after two hours of application and is safe to use in both the vaginal and rectal compartments. Our study provides support for the development of silk fibroin as a highly promising, user-friendly HIV prevention modality to address the global disparity in HIV infection.
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http://dx.doi.org/10.1002/jia2.25628DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7569169PMC
October 2020

Rapid Induction of Multifunctional Antibodies in Rabbits and Macaques by Clade C HIV-1 CAP257 Envelopes Circulating During Epitope-Specific Neutralization Breadth Development.

Front Immunol 2020 2;11:984. Epub 2020 Jun 2.

Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, United States.

We report here on HIV-1 immunization results in rabbits and macaques co-immunized with clade C gp160 DNA and gp140 trimeric envelope vaccines, a strategy similar to a recent clinical trial that showed improved speed and magnitude of humoral responses. Clade C envelopes were isolated from CAP257, an individual who developed a unique temporal pattern of neutralization breadth development, comprising three separate "Waves" targeting distinct Env epitopes and different HIV clades. We used phylogeny and neutralization criteria to down-select envelope vaccine candidates, and confirmed antigenicity of our antigens by interaction with well-characterized broadly neutralizing monoclonal antibodies. Using these envelopes, we performed rabbit studies that screened for immunogenicity of CAP257 Envs from timepoints preceding peak neutralization breadth in each Wave. Selected CAP257 envelopes from Waves 1 and 2, during the first 2 years of infection that were highly immunogenic in rabbits were then tested in macaques. We found that in rabbits and macaques, co-immunization of DNA, and protein envelope-based vaccines induced maximum binding and neutralizing antibody titers with three immunizations. No further benefit was obtained with additional immunizations. The vaccine strategies recapitulated the Wave-specific epitope targeting observed in the CAP257 participant, and elicited Tier 1A, 1B, and Tier 2 heterologous neutralization. CAP257 envelope immunogens also induced the development of ADCC and T responses in macaques, and these responses positively correlated with heterologous neutralization. Together, the results from two animal models in this study have implications for identifying effective vaccine immunogens. We used a multi-step strategy to (1) select an Env donor with well-characterized neutralization breadth development; (2) study Env phylogeny for potential immunogens circulating near peak breadth timepoints during the first 2 years of infection; (3) test down-selected Envs for antigenicity; (4) screen down-selected Envs in an effective vaccine regimen in rabbits; and (5) advance the most immunogenic Envs to NHP studies. The results were an induction of high titers of HIV-1 envelope-specific antibodies with increasing avidity and cross-clade neutralizing antibodies with effector functions that together may improve the potential for protection in a pre-clinical SHIV model.
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http://dx.doi.org/10.3389/fimmu.2020.00984DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7280454PMC
June 2020

Persistence of HIV-1 Env-Specific Plasmablast Lineages in Plasma Cells after Vaccination in Humans.

Cell Rep Med 2020 May;1(2)

Infectious Diseases Division, University of Alabama at Birmingham, Birmingham, AL, USA.

Induction of persistent HIV-1 Envelope (Env) specific antibody (Ab) is a primary goal of HIV vaccine strategies; however, it is unclear whether HIV Env immunization in humans induces bone marrow plasma cells, the presumed source of long-lived systemic Ab. To define the features of Env-specific plasma cells after vaccination, samples were obtained from HVTN 105, a phase I trial testing the same gp120 protein immunogen, AIDSVAX B/E, used in RV144, along with a DNA immunogen in various prime and boost strategies. Boosting regimens that included AIDSVAX B/E induced robust peripheral blood plasmablast responses. The Env-specific immunoglobulin repertoire of the plasmablasts is dominated by VH1 gene usage and targeting of the V3 region. Numerous plasmablast-derived immunoglobulin lineages persisted in the bone marrow >8 months after immunization, including in the CD138 long-lived plasma cell compartment. These findings identify a cellular linkage for the development of sustained Env-specific Abs following vaccination in humans.
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http://dx.doi.org/10.1016/j.xcrm.2020.100015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7311075PMC
May 2020

An HIV Vaccine Targeting the V2 Region of the HIV Envelope Induces a Highly Durable Polyfunctional Fc-Mediated Antibody Response in Rhesus Macaques.

J Virol 2020 08 17;94(17). Epub 2020 Aug 17.

Department of Medicine, Division of Infectious Diseases, Icahn School of Medicine at Mount Sinai, New York, New York, USA.

The HIV vaccine field now recognizes the potential importance of generating polyfunctional antibodies (Abs). The only clinical HIV vaccine trial to date to show significant efficacy (RV144) found that reduced infection rates correlated with the level of nonneutralizing Abs specific for the V2 region of the envelope glycoprotein. We have conducted a comprehensive preclinical reverse vaccinology-based vaccine program that has included the design and production and testing of numerous scaffolded V2 region immunogens. The most immunogenic vaccine regimen in nonhuman primates among those studied as part of this program consisted of a cocktail of three immunogens presenting V2 from different viruses and clades in the context of different scaffolds. Presently we demonstrate that the V2-specific Ab response from this regimen was highly durable and functionally diverse for the duration of the study (25 weeks after the final immunization). The total IgG binding response at this late time point exhibited only an ∼5× reduction in potency. Three immunizations appeared essential for the elicitation of a strong Ab-dependent cellular cytotoxicity (ADCC) response for all animals, as opposed to the Ab-dependent cellular phagocytosis (ADCP) and virus capture responses, which were comparably potent after only 2 immunizations. All functionalities measured were highly durable through the study period. Therefore, testing this vaccine candidate for its protective capacity is warranted. The only HIV vaccine trial for which protective efficacy was detected correlated this efficacy with V2-specific Abs that were effectively nonneutralizing. This result has fueled a decade of HIV vaccine research focused on designing an HIV vaccine capable of eliciting V2-focused, polyfunctional Abs that effectively bind HIV and trigger various leukocytes to kill the virus and restrict viral spread. From the numerous vaccine candidates designed and tested as part of our V2-focused preclinical vaccine program, we have identified immunogens and a vaccine regimen that induces a highly durable and polyfunctional V2-focused Ab response in rhesus macaques, described herein.
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http://dx.doi.org/10.1128/JVI.01175-20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7431793PMC
August 2020

Cloning and functional testing of rhesus macaque (Macaca mulatta) IL-9 and IL-33.

J Med Primatol 2020 06 4;49(3):144-152. Epub 2020 Feb 4.

Infectious Diseases Division, University of Alabama at Birmingham, Birmingham, AL, USA.

Background: IL-9 and IL-33 can profoundly influence immune responses. As a necessary first step toward defining their impact in the rhesus macaque model, we confirmed their endogenous expression and sequence identity and generated expression vectors for the recombinant expression of rhesus IL-9 and IL-33.

Methods: RT-PCR and Sanger sequencing was used to define the expression and sequences for rhesus IL-9 and IL-33. The resulting recombinant cytokines were tested by ELISA and proliferation assays.

Results: Full-length rhesus IL-9 and the mature form of rhesus IL-33 share 78% and 73% nucleotide similarity, respectively, with humans. Both cytokines are expressed in lymphocytes, with IL-9 expression also evident in CD4+ T cells. Recombinantly expressed rhesus IL-9 and IL-33 were each biologically active in vitro, including enhancing the proliferation of a rhesus B cell line.

Conclusions: The recombinant rhesus IL-9 and IL-33 constructs produce biologically active cytokines that can act upon rhesus B cells.
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http://dx.doi.org/10.1111/jmp.12464DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7198344PMC
June 2020

Single-dose bNAb cocktail or abbreviated ART post-exposure regimens achieve tight SHIV control without adaptive immunity.

Nat Commun 2020 01 7;11(1):70. Epub 2020 Jan 7.

Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, OR, USA.

Vertical transmission accounts for most human immunodeficiency virus (HIV) infection in children, and treatments for newborns are needed to abrogate infection or limit disease progression. We showed previously that short-term broadly neutralizing antibody (bNAb) therapy given 24 h after oral exposure cleared simian-human immunodeficiency virus (SHIV) in a macaque model of perinatal infection. Here, we report that all infants given either a single dose of bNAbs at 30 h, or a 21-day triple-drug ART regimen at 48 h, are aviremic with almost no virus in tissues. In contrast, bNAb treatment beginning at 48 h leads to tight control without adaptive immune responses in half of animals. We conclude that both bNAbs and ART mediate effective post-exposure prophylaxis in infant macaques within 30-48 h of oral SHIV exposure. Our findings suggest that optimizing the treatment regimen may extend the window of opportunity for preventing perinatal HIV infection when treatment is delayed.
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http://dx.doi.org/10.1038/s41467-019-13972-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6946664PMC
January 2020

A Meta-analysis of Passive Immunization Studies Shows that Serum-Neutralizing Antibody Titer Associates with Protection against SHIV Challenge.

Cell Host Microbe 2019 Sep;26(3):336-346.e3

Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N., Seattle, WA 98109, USA; Department of Biostatistics, University of Washington, Seattle, WA 98195, USA. Electronic address:

Passively administered broadly neutralizing antibodies (bNAbs) targeting the HIV-1 envelope glycoprotein (Env) have been shown to protect non-human primates (NHPs) against chimeric simian-human immunodeficiency virus (SHIV) infection. With data from multiple non-human primate SHIV challenge studies that used single bNAbs, we conducted a meta-analysis to examine the relationship between predicted serum 50% neutralization titer (ID50) against the challenge virus and infection outcome. In a logistic model that adjusts for bNAb epitopes and challenge viruses, serum ID50 had a highly significant effect on infection risk (p < 0.001). The estimated ID50 to achieve 50%, 75%, and 95% protection was 91 (95% confidence interval [CI]: 55, 153), 219 (117, 410), and 685 (319, 1471), respectively. This analysis indicates that serum neutralizing titer against the relevant virus is a key parameter of protection and that protection from acquisition by a single bNAb might require substantial levels of neutralization at the time of exposure.
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http://dx.doi.org/10.1016/j.chom.2019.08.014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6755677PMC
September 2019

Multimeric Epitope-Scaffold HIV Vaccines Target V1V2 and Differentially Tune Polyfunctional Antibody Responses.

Cell Rep 2019 07;28(4):877-895.e6

Department of Medicine, Division of Infectious Diseases, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. Electronic address:

The V1V2 region of the HIV-1 envelope is the target of several broadly neutralizing antibodies (bNAbs). Antibodies to V1V2 elicited in the RV144 clinical trial correlated with a reduced risk of HIV infection, but these antibodies were without broad neutralizing activity. Antibodies targeting V1V2 also correlated with a reduced viral load in immunized macaques challenged with simian immunodeficiency virus (SIV) or simian/human immunodeficiency virus (SHIV). To focus immune responses on V1V2, we engrafted the native, glycosylated V1V2 domain onto five different multimeric scaffold proteins and conducted comparative immunogenicity studies in macaques. Vaccinated macaques developed high titers of plasma and mucosal antibodies that targeted structurally distinct V1V2 epitopes. Plasma antibodies displayed limited neutralizing activity but were functionally active for ADCC and phagocytosis, which was detectable 1-2 years after immunizations ended. This study demonstrates that multivalent, glycosylated V1V2-scaffold protein immunogens focus the antibody response on V1V2 and are differentially effective at inducing polyfunctional antibodies with characteristics associated with protection.
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http://dx.doi.org/10.1016/j.celrep.2019.06.074DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6666430PMC
July 2019

Antibodies Tip the Balance Towards an HIV Cure.

Trends Immunol 2019 05;40(5):375-377

Pathobiology and Immunology Division, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA.

Long-term drug therapy for HIV-1 infection can prevent both disease progression and virus transmission, but treatment does not eradicate the virus. A new gene therapy study (Immunity 2019;50:567-575.e5) using human antibodies shows significant promise for a functional cure in a non-human primate model.
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http://dx.doi.org/10.1016/j.it.2019.03.008DOI Listing
May 2019

IL-33 enhances the kinetics and quality of the antibody response to a DNA and protein-based HIV-1 Env vaccine.

Vaccine 2019 04 27;37(17):2322-2330. Epub 2019 Mar 27.

Infectious Diseases Division, University of Rochester Medical Center, Rochester, NY, United States. Electronic address:

Induction of a sustained and broad antibody (Ab) response is a major goal in developing a protective HIV-1 vaccine. DNA priming alone shows reduced levels of immunogenicity; however, when combined with protein boosting is an attractive vaccination strategy for induction of humoral responses. Using the VC10014 DNA and protein-based vaccine consisting of HIV-1 envelope (Env) gp160 plasmids and trimeric gp140 proteins derived from an HIV-1 clade B infected subject who developed broadly neutralizing serum Abs, and which has been previously demonstrated to induce Tier 2 heterologous neutralizing Abs in rhesus macaques, we evaluated whether MPLA and IL-33 when administered during the DNA priming phase enhances the humoral response in mice. The addition of IL-33 during the gp160 DNA priming phase resulted in high titer gp120-specific plasma IgG after the first immunization. The IL-33 treated mice had higher plasma IgG Ab avidity, breadth, and durability after DNA and protein co-immunization with alum adjuvant as compared to MPLA and alum only treated mice. IL-33 was also associated with a significant IgM Env-specific response and expansion of peritoneal and splenic B-1b B cells. These results indicate that DNA priming in the presence of exogenous IL-33 qualitatively alters the HIV-1 Env-specific humoral response, improving the kinetics and breadth of potentially protective Ab.
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http://dx.doi.org/10.1016/j.vaccine.2019.03.044DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6506229PMC
April 2019

Divergent HIV-1-Directed Immune Responses Generated by Systemic and Mucosal Immunization with Replicating Single-Cycle Adenoviruses in Rhesus Macaques.

J Virol 2019 05 1;93(10). Epub 2019 May 1.

Department of Molecular Medicine, Mayo Clinic, Rochester, Minnesota, USA

Most human immunodeficiency virus type 1 (HIV-1) infections begin at mucosal surfaces. Providing a barrier of protection at these may assist in combating the earliest events in infection. Systemic immunization by intramuscular (i.m.) injection can drive mucosal immune responses, but there are data suggesting that mucosal immunization can better educate these mucosal immune responses. To test this, rhesus macaques were immunized with replicating single-cycle adenovirus (SC-Ad) vaccines expressing clade B HIV-1 gp160 by the intranasal (i.n.) and i.m. routes to compare mucosal and systemic routes of vaccination. SC-Ad vaccines generated significant circulating antibody titers against Env after a single i.m. immunization. Switching the route of second immunization with the same SC-Ad serotype allowed a significant boost in these antibody levels. When these animals were boosted with envelope protein, envelope-binding antibodies were amplified 100-fold, but qualitatively different immune responses were generated. Animals immunized by only the i.m. route had high peripheral T follicular helper (pTfh) cell counts in blood but low Tfh cell counts in lymph nodes. Conversely, animals immunized by the i.n. route had high Tfh cell counts in lymph nodes but low pTfh cell counts in the blood. Animals immunized by only the i.m. route had lower antibody-dependent cellular cytotoxicity (ADCC) antibody activity, whereas animals immunized by the mucosal i.n. route had higher ADCC antibody activity. When these Env-immunized animals were challenged rectally with simian-human immunodeficiency virus (SHIV) strain SF162P3 (SHIV), they all became infected. However, mucosally SC-Ad-immunized animals had lower viral loads in their gastrointestinal tracts. These data suggest that there may be benefits in educating the immune system at mucosal sites during HIV vaccination. HIV-1 infections usually start at a mucosal surface after sexual contact. Creating a barrier of protection at these mucosal sites may be a good strategy for to protect against HIV-1 infections. While HIV-1 enters at mucosa, most vaccines are not delivered here. Most are instead injected into the muscle, a site well distant and functionally different than mucosal tissues. This study tested if delivering HIV vaccines at mucosa or in the muscle makes a difference in the quality, quantity, and location of immune responses against the virus. These data suggest that there are indeed advantages to educating the immune system at mucosal sites with an HIV-1 vaccine.
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http://dx.doi.org/10.1128/JVI.02016-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6498041PMC
May 2019

Reduced Cell-Associated DNA and Improved Viral Control in Macaques following Passive Transfer of a Single Anti-V2 Monoclonal Antibody and Repeated Simian/Human Immunodeficiency Virus Challenges.

J Virol 2018 06 14;92(11). Epub 2018 May 14.

Oregon National Primate Research Center, Oregon Health & Science University, Portland, Oregon, USA

A high level of V1V2-specific IgG antibodies (Abs) in vaccinees' sera was the only independent variable that correlated with a reduced risk of human immunodeficiency virus (HIV) acquisition in the RV144 clinical trial. In contrast, IgG avidity, antibody neutralization, and antibody-dependent cellular cytotoxicity each failed as independent correlates of infection. Extended analyses of RV144 samples demonstrated the antiviral activities of V1V2-specific vaccine-induced antibodies. V2-specific antibodies have also been associated with protection from simian immunodeficiency virus (SIV), and the V2i-specific subset of human monoclonal antibodies (MAbs), while poor neutralizers, mediates Fc-dependent antiviral functions The objective of this study was to determine the protective efficacy of a V2i-specific human MAb, 830A, against mucosal simian/human immunodeficiency virus (SHIV) challenge. V2i MAb binding sites overlap the integrin binding site in the V2 region and are similar to the epitopes bound by antibodies associated with reduced HIV infection rates in RV144. Because the IgG3 subclass was a correlate of reduced infection rates in RV144, we compared passive protection by both IgG1 and IgG3 subclasses of V2i MAb 830A. This experiment represents the first test of the hypothesis emanating from RV144 and SIV studies that V2i Abs can reduce the risk of infection. The results show that passive transfer with a single V2i MAb, IgG1 830A, reduced plasma and peripheral blood mononuclear cell (PBMC) virus levels and decreased viral DNA in lymphoid tissues compared to controls, but too few animals remained uninfected to achieve significance in reducing the risk of infection. Based on these findings, we conclude that V2i antibodies can impede virus seeding following mucosal challenge, resulting in improved virus control. Since the results of the HIV RV144 clinical trial were reported, there has been significant interest in understanding how protection was mediated. Antibodies directed to a subregion of the envelope protein called V1V2 were directly correlated with a reduced risk, and surprisingly low virus neutralization was observed. To determine whether these antibodies alone could mediate protection, we used a human monoclonal antibody directed to V2 with properties similar to those elicited in the vaccine trial for passive infusions in rhesus macaques and challenge with SHIV. The single V2 antibody at the dose given did not significantly reduce the number of infections, but there was a significant reduction in the seeding of virus to the lymph nodes and a decrease in plasma viremia in the HIV antibody-infused macaques compared with the control antibody-infused animals. This finding shows that V2 antibodies mediate antiviral activities that could contribute to a protective HIV vaccine.
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http://dx.doi.org/10.1128/JVI.02198-17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5952134PMC
June 2018

Passive and active antibody studies in primates to inform HIV vaccines.

Expert Rev Vaccines 2018 02 19;17(2):127-144. Epub 2018 Jan 19.

a Division of Pathobiology & Immunology, Oregon National Primate Research Center , Oregon Health & Science University , Beaverton , OR , USA.

Introduction: Prevention of infection remains the ultimate goal for HIV vaccination, and there is compelling evidence that antibodies directed to Envelope are necessary to block infection. Generating antibodies that are sufficiently broad, potent, and sustained to block infection by the diverse HIV-1 strains circulating worldwide remains an area of intense study.

Areas Covered: In this review, we have summarized progress from publications listed as PubMed citations in 2016-17 in the areas of passive antibody studies using human neutralizing monoclonal antibodies in nonhuman primates, HIV Envelope vaccine development and active vaccination studies to generate potent neutralizing antibodies.

Expert Commentary: Passive transfer studies in nonhuman primates using human neutralizing monoclonal antibodies have informed the potency, specificity, and cooperativity of antibodies needed to prevent infection, leading to clinical studies now testing potent antibodies for prevention of HIV. Progress in understanding the structure of Envelope has led to novel vaccine constructs, including mimetics, scaffolds and native-like proteins. As yet, no single approach ensures protection against the circulating global HIV-1 strains, but there is progress in understanding why, and intense research continues in these and other areas for a solution. We offer perspectives on how this knowledge may shape the design of future HIV vaccines.
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http://dx.doi.org/10.1080/14760584.2018.1425619DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6587971PMC
February 2018

Pre-existing neutralizing antibody mitigates B cell dysregulation and enhances the Env-specific antibody response in SHIV-infected rhesus macaques.

PLoS One 2017 21;12(2):e0172524. Epub 2017 Feb 21.

Division of Infectious Diseases, Department of Medicine, University of Rochester Medical Center, Rochester, New York, United States of America.

Our central hypothesis is that protection against HIV infection will be powerfully influenced by the magnitude and quality of the B cell response. Although sterilizing immunity, mediated by pre-formed abundant and potent antibodies is the ultimate goal for B cell-targeted HIV vaccine strategies, scenarios that fall short of this may still confer beneficial defenses against viremia and disease progression. We evaluated the impact of sub-sterilizing pre-existing neutralizing antibody on the B cell response to SHIV infection. Adult male rhesus macaques received passive transfer of a sub-sterilizing amount of polyclonal neutralizing immunoglobulin (Ig) purified from previously infected animals (SHIVIG) or control Ig prior to intra-rectal challenge with SHIVSF162P4 and extensive longitudinal sampling was performed. SHIVIG treated animals exhibited significantly reduced viral load and increased de novo Env-specific plasma antibody. Dysregulation of the B cell profile was grossly apparent soon after infection in untreated animals; exemplified by a ≈50% decrease in total B cells in the blood evident 2-3 weeks post-infection which was not apparent in SHIVIG treated animals. IgD+CD5+CD21+ B cells phenotypically similar to marginal zone-like B cells were highly sensitive to SHIV infection, becoming significantly decreased as early as 3 days post-infection in control animals, while being maintained in SHIVIG treated animals, and were highly correlated with the induction of Env-specific plasma antibody. These results suggest that B cell dysregulation during the early stages of infection likely contributes to suboptimal Env-specific B cell and antibody responses, and strategies that limit this dysregulation may enhance the host's ability to eliminate HIV.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0172524PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5319772PMC
August 2017

Differential induction of anti-V3 crown antibodies with cradle- and ladle-binding modes in response to HIV-1 envelope vaccination.

Vaccine 2017 03 6;35(10):1464-1473. Epub 2017 Feb 6.

Department of Medicine, Division of Infectious Diseases, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; James J. Peters VA Medical Center, Bronx, NY 10468, USA. Electronic address:

The V3 loop in the HIV envelope gp120 is one of the immunogenic sites targeted by Abs. The V3 crown in particular has conserved structural elements recognized by cross-reactive neutralizing Abs, indicating its potential contribution in protection against HIV. Crystallographic analyses of anti-V3 crown mAbs in complex with the V3 peptides have revealed that these mAbs recognize the conserved sites on the V3 crown via two distinct strategies: a cradle-binding mode (V3C) and a ladle-binding (V3L) mode. However, almost all of the anti-V3 crown mAbs studied in the past were isolated from chronically HIV-infected individuals. The extents to which the two types of anti-V3 crown Abs are generated by vaccination are unknown. This study analyzed the prevalence of V3C-type and V3L-type Ab responses in HIV-infected individuals and in HIV envelope-immunized humans and animals using peptide mimotopes that distinguish the two Ab types. The results show that both V3L-type and V3C-type Abs were generated by the vast majority of chronically HIV-infected humans, although the V3L-type were more prevalent. In contrast, only one of the two V3 Ab types was elicited in vaccinated humans or animal models, irrespective of HIV-1 envelope clades, envelope constructs (oligomeric or monomeric), and protocols (DNA plus protein or protein alone) used for vaccinations. The V3C-type Abs were produced by vaccinated humans, macaques, and rabbits, whereas the V3L-type Abs were made by mice. The V3C-type and V3L-type Abs generated by the vaccinations were able to mediate virus neutralization. These data indicate the restricted repertoires and the species-specific differences in the functional V3-specific Ab responses induced by the HIV envelope vaccines. The study implies the need for improving immunogen designs and vaccination strategies to broaden the diversity of Abs in order to target the different conserved epitopes in the V3 loop and, by extension, in the entire HIV envelope.
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http://dx.doi.org/10.1016/j.vaccine.2016.11.107DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5343672PMC
March 2017

Use of broadly neutralizing antibodies for HIV-1 prevention.

Immunol Rev 2017 01;275(1):296-312

Oregon National Primate Center, Oregon Health & Science University, Beaverton, OR, USA.

Antibodies have a long history in antiviral therapy, but until recently, they have not been actively pursued for HIV-1 due to modest potency and breadth of early human monoclonal antibodies (MAbs) and perceived insurmountable technical, financial, and logistical hurdles. Recent advances in the identification and characterization of MAbs with the ability to potently neutralize diverse HIV-1 isolates have reinvigorated discussion and testing of these products in humans, since new broadly neutralizing MAbs (bnMAbs) are more likely to be effective against worldwide strains of HIV-1. In animal models, there is abundant evidence that bnMAbs can block infection in a dose-dependent manner, and the more potent bnMAbs will allow clinical testing at infusion doses that are practically achievable. Moreover, recent advances in antibody engineering are providing further improvements in MAb potency, breadth, and half-life. This review summarizes the current state of the field of bnMAb protection in animal models as well as a review of variables that are critical for antiviral activity. Several bnMAbs are currently in clinical testing, and we offer perspectives on their use as pre-exposure prophylaxis (PrEP), potential benefits beyond sterilizing immunity, and a discussion of future approaches to engineer novel molecules.
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http://dx.doi.org/10.1111/imr.12511DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5314445PMC
January 2017

Induction of neutralizing antibodies in rhesus macaques using V3 mimotope peptides.

Vaccine 2016 05 19;34(24):2713-21. Epub 2016 Apr 19.

Department of Pathology, New York University School of Medicine, New York, NY, USA. Electronic address:

RV144 vaccinees with low HIV-1 Envelope-specific IgA antibodies (Abs) also had Abs directed to the hypervariable region 3 (V3) that inversely correlated with infection risk. Thus, anti-V3 HIV-1 Abs may contribute to protection from HIV-1 infection. The V3 region contains two dominant clusters of epitopes; one is preferentially recognized by mAbs encoded by VH5-51 and VL lambda genes, while the second one is recognized by mAbs encoded by other VH genes. We designed a study in rhesus macaques to induce anti-V3 Abs specific to each of these two dominant clusters of V3 epitopes to test whether the usage of the VH5-51 gene results in different characteristics of antibodies. The two C4-V3 immunogens used for immunization were each comprised of a fusion of the C4 peptide containing the T cell epitope and a V3 mimotope peptide mimicking the V3 epitope. The C4-447 peptide was designed to target B cells with several VH1-VH4 genes, the C4-VH5-51 peptide was designed to specifically target B cells with the VH5-51 gene. Six animals in two groups were immunized five times with these two immunogens, and screening of 10 sequential plasma samples post immunization demonstrated that C4-447 induced higher titers of plasma anti-V3 Abs and significantly more potent neutralizing activities against tier 1 and some tier 2 pseudoviruses than C4-VH5-51. Levels of anti-V3 Abs in buccal secretions were significantly higher in sequential samples derived from C4-447- than from C4-VH5-51-immunized animals. The titers of anti-V3 Abs in plasma strongly correlated with their levels in mucosal secretions. The results show that high titers of vaccine-induced anti-V3 Abs in plasma determine the potency and breadth of neutralization, as well as the rate of transduction of Abs to mucosal tissues, where they can play a role in preventing HIV-1 infection.
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http://dx.doi.org/10.1016/j.vaccine.2016.04.027DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4874195PMC
May 2016

Early short-term treatment with neutralizing human monoclonal antibodies halts SHIV infection in infant macaques.

Nat Med 2016 Apr 21;22(4):362-8. Epub 2016 Mar 21.

Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, Oregon, USA.

Prevention of mother-to-child transmission (MTCT) of HIV remains a major objective where antenatal care is not readily accessible. We tested HIV-1-specific human neutralizing monoclonal antibodies (NmAbs) as a post-exposure therapy in an infant macaque model for intrapartum MTCT. One-month-old rhesus macaques were inoculated orally with the simian-human immunodeficiency virus SHIVSF162P3. On days 1, 4, 7 and 10 after virus exposure, we injected animals subcutaneously with NmAbs and quantified systemic distribution of NmAbs in multiple tissues within 24 h after antibody administration. Replicating virus was found in multiple tissues by day 1 in animals that were not treated. All NmAb-treated macaques were free of virus in blood and tissues at 6 months after exposure. We detected no anti-SHIV T cell responses in blood or tissues at necropsy, and no virus emerged after CD8(+) T cell depletion. These results suggest that early passive immunotherapy can eliminate early viral foci and thereby prevent the establishment of viral reservoirs.
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http://dx.doi.org/10.1038/nm.4063DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4983100PMC
April 2016

Achieving Potent Autologous Neutralizing Antibody Responses against Tier 2 HIV-1 Viruses by Strategic Selection of Envelope Immunogens.

J Immunol 2016 Apr 4;196(7):3064-78. Epub 2016 Mar 4.

Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006; Molecular Microbiology and Immunology, School of Medicine, Oregon Health & Science University, Portland, OR 97239

Advancement in immunogen selection and vaccine design that will rapidly elicit a protective Ab response is considered critical for HIV vaccine protective efficacy. Vaccine-elicited Ab responses must therefore have the capacity to prevent infection by neutralization-resistant phenotypes of transmitted/founder (T/F) viruses that establish infection in humans. Most vaccine candidates to date have been ineffective at generating Abs that neutralize T/F or early variants. In this study, we report that coimmunizing rhesus macaques with HIV-1 gp160 DNA and gp140 trimeric protein selected from native envelope gene sequences (envs) induced neutralizing Abs against Tier 2 autologous viruses expressing cognate envelope (Env). The Env immunogens were selected from envs emerging during the earliest stages of neutralization breadth developing within the first 2 years of infection in two clade B-infected human subjects. Moreover, the IgG responses in macaques emulated the targeting to specific regions of Env known to be associated with autologous and heterologous neutralizing Abs developed within the human subjects. Furthermore, we measured increasing affinity of macaque polyclonal IgG responses over the course of the immunization regimen that correlated with Tier 1 neutralization. In addition, we report firm correlations between Tier 2 autologous neutralization and Tier 1 heterologous neutralization, as well as overall TZM-bl breadth scores. Additionally, the activation of Env-specific follicular helper CD4 T cells in lymphocytes isolated from inguinal lymph nodes of vaccinated macaques correlated with Tier 2 autologous neutralization. These results demonstrate the potential for native Env derived from subjects at the time of neutralization broadening as effective HIV vaccine elements.
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http://dx.doi.org/10.4049/jimmunol.1500527DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4797725PMC
April 2016

Functional and Molecular Characteristics of Novel and Conserved Cross-Clade HIV Envelope Specific Human Monoclonal Antibodies.

Monoclon Antib Immunodiagn Immunother 2015 Apr;34(2):65-72

1 Division of Infectious Diseases, University of Rochester Medical Center , Rochester, New York.

To define features of the B cell response to HIV that may be translated to vaccine development, we have isolated a panel of monoclonal antibodies (MAbs) from HIV-infected patients. These MAbs are all highly reactive to HIV envelope (Env) from multiple clades, and include gp120 and gp41 specificities. Three of the MAbs exhibit substantial homology to previously described VH1-69, VH3-30, and VH4-59 HIV broadly neutralizing antibody lineages. An inherently autoreactive VH4-34 encoded MAb was reactive to diverse Env despite its minimal mutation from germline. Its isolation is consistent with our previous observation of increased VH4-34+antibodies in HIV-infected patients. These results suggest that conserved developmental processes contribute to immunoglobulin repertoire usage and maturation in response to HIV Env and that intrinsically autoreactive VH genes, despite the absence of mutation, could serve as effective templates for maturation and development of protective antibodies. These results also bear significant implications for the development of immunogens.
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http://dx.doi.org/10.1089/mab.2014.0064DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4410305PMC
April 2015

Animal models in HIV-1 protection and therapy.

Curr Opin HIV AIDS 2015 May;10(3):170-6

Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, Oregon, USA.

Purpose Of Review: The purpose of this review is to highlight major advances in the development and use of animal models for HIV-1 research during the last year.

Recent Findings: Animal model research during the last year has focused on the development and refinement of models; use of these models to explore key questions about HIV entry, immune control, and persistence; and key discoveries with these models testing therapeutic and vaccine concepts. Some of the greatest breakthroughs have been in understanding early events surrounding transmission, the effectiveness of broadly neutralizing human monoclonal antibodies as passive prophylaxis, and some new ideas in the area of eliminating the viral reservoir in established infection.

Summary: Despite the lack of a flawless HIV-1 infection and pathogenesis model, the field utilizes several models that have already made important contributions to our understanding of early events, immune control, and the potential for novel therapies.
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http://dx.doi.org/10.1097/COH.0000000000000152DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4526147PMC
May 2015

Envelope variants circulating as initial neutralization breadth developed in two HIV-infected subjects stimulate multiclade neutralizing antibodies in rabbits.

J Virol 2014 Nov 10;88(22):12949-67. Epub 2014 Sep 10.

Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, Oregon, USA Department of Molecular Microbiology & Immunology, Oregon Health & Science University, Portland, Oregon, USA

Unlabelled: Identifying characteristics of the human immunodeficiency virus type 1 (HIV-1) envelope that are effective in generating broad, protective antibodies remains a hurdle to HIV vaccine design. Emerging evidence of the development of broad and potent neutralizing antibodies in HIV-infected subjects suggests that founder and subsequent progeny viruses may express unique antigenic motifs that contribute to this developmental pathway. We hypothesize that over the course of natural infection, B cells are programmed to develop broad antibodies by exposure to select populations of emerging envelope quasispecies variants. To test this hypothesis, we identified two unrelated subjects whose antibodies demonstrated increasing neutralization breadth against a panel of HIV-1 isolates over time. Full-length functional env genes were cloned longitudinally from these subjects from months after infection through 2.6 to 5.8 years of infection. Motifs associated with the development of breadth in published, cross-sectional studies were found in both subjects. We compared the immunogenicity of envelope vaccines derived from time points obtained during and after broadening of neutralization activity within these subjects. Rabbits were coimmunized four times with selected multiple gp160 DNAs and gp140-trimeric envelope proteins. The affinity of the polyclonal response increased as a function of boosting. The most rapid and persistent neutralization of multiclade tier 1 viruses was elicited by envelopes that were circulating in plasma at time points prior to the development of 50% neutralization breadth in both human subjects. The breadth elicited in rabbits was not improved by exposure to later envelope variants. These data have implications for vaccine development in describing a target time point to identify optimal envelope immunogens.

Importance: Vaccine protection against viral infections correlates with the presence of neutralizing antibodies; thus, vaccine components capable of generating potent neutralization are likely to be critical constituents in an effective HIV vaccine. However, vaccines tested thus far have elicited only weak antibody responses and very modest, waning protection. We hypothesized that B cells develop broad antibodies by exposure to the evolving viral envelope population and tested this concept using multiple envelopes from two subjects who developed neutralization breadth within a few years of infection. We compared different combinations of envelopes from each subject to identify the most effective immunogens and regimens. In each subject, use of HIV envelopes circulating during the early development and maturation of breadth generated more-potent antibodies that were modestly cross neutralizing. These data suggest a new approach to identifying envelope immunogens that may be more effective in generating protective antibodies in humans.
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http://dx.doi.org/10.1128/JVI.01812-14DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4249069PMC
November 2014

Emergence of broadly neutralizing antibodies and viral coevolution in two subjects during the early stages of infection with human immunodeficiency virus type 1.

J Virol 2014 Nov 13;88(22):12968-81. Epub 2014 Aug 13.

Seattle Biomedical Research Institute, Seattle, Washington, USA Department of Global Health, University of Washington, Seattle, Washington, USA

Unlabelled: Delineating the key early events that lead to the development of broadly neutralizing anti-HIV-1 antibodies during natural infection may help guide the development of immunogens and vaccine regimens to prevent HIV-1 infection. In this study, we monitored two HIV-1-positive subjects, VC20013 and VC10014, over the course of infection from before they developed broadly neutralizing antibody (bNAb) activity until several years after neutralizing breadth was detected in plasma. Both subjects developed bNAb activity after approximately 1 year postinfection, which ultimately mapped to the membrane-proximal external region (MPER) in VC20013 and an epitope that overlaps the CD4 receptor binding site in VC10014. In subject VC20013, we were able to identify anti-MPER activity in the earliest plasma sample that exhibited no bNAb activity, indicating that this epitope specificity was acquired very early on, but that it was initially not able to mediate neutralization. Escape mutations within the bNAb epitopes did not arise in the circulating envelopes until bNAb activity was detectable in plasma, indicating that this early response was not sufficient to drive viral escape. As bNAb activity began to emerge in both subjects, we observed a simultaneous increase in autologous antienvelope antibody binding affinity, indicating that antibody maturation was occurring as breadth was developing. Our findings illustrate one potential mechanism by which bNAbs develop during natural infection in which an epitope target is acquired very early on during the course of infection but require time and maturation to develop into broadly neutralizing activity.

Importance: One major goal of HIV-1 vaccine research is the development of a vaccine that can elicit broadly neutralizing antibodies (bNAbs). Although no such vaccine exists, bNAbs develop in approximately 20% of HIV-1-infected subjects, providing a prototype of the bNAbs that must be reelicited by vaccine. Thus, there is significant interest in understanding the mechanisms by which bNAbs develop during the course of infection. We studied the timing, epitope specificity, and evolution of the bNAb responses in two HIV-1-positive patients who developed bNAb activity within the first several years after infection. In one subject, antibodies to a broadly neutralizing epitope developed very early but were nonneutralizing. After several months, neutralizing activity developed, and the virus mutated to escape their activity. Our study highlights one mechanism for the development of bNAbs where early epitope acquisition followed by sufficient time for antibody maturation drives the epitope-specific antibody response toward broadly neutralizing activity.
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http://dx.doi.org/10.1128/JVI.01816-14DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4249098PMC
November 2014

The MHC class II cofactor HLA-DM interacts with Ig in B cells.

J Immunol 2014 Sep 6;193(6):2641-2650. Epub 2014 Aug 6.

Department of Pediatrics, Program in Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA.

B cells internalize extracellular Ag into endosomes using the Ig component of the BCR. In endosomes, Ag-derived peptides are loaded onto MHC class II proteins. How these pathways intersect remains unclear. We find that HLA-DM (DM), a catalyst for MHC class II peptide loading, coprecipitates with Ig in lysates from human tonsillar B cells and B cell lines. The molecules in the Ig/DM complexes have mature glycans, and the complexes colocalize with endosomal markers in intact cells. A larger fraction of Ig precipitates with DM after BCR crosslinking, implying that complexes can form when DM meets endocytosed Ig. In vitro, in the endosomal pH range, soluble DM directly binds the Ig Fab domain and increases levels of free Ag released from immune complexes. Taken together, these results argue that DM and Ig intersect in the endocytic pathway of B cells with potential functional consequences.
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http://dx.doi.org/10.4049/jimmunol.1400075DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4157100PMC
September 2014

Neutralizing polyclonal IgG present during acute infection prevents rapid disease onset in simian-human immunodeficiency virus SHIVSF162P3-infected infant rhesus macaques.

J Virol 2013 Oct 24;87(19):10447-59. Epub 2013 Jul 24.

Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, Oregon, USA.

Simian-human immunodeficiency virus (SHIV) models for human immunodeficiency virus (HIV) infection have been widely used in passive studies with HIV neutralizing antibodies (NAbs) to test for protection against infection. However, because SHIV-infected adult macaques often rapidly control plasma viremia and any resulting pathogenesis is minor, the model has been unsuitable for studying the impact of antibodies on pathogenesis in infected animals. We found that SHIVSF162P3 infection in 1-month-old rhesus macaques not only results in high persistent plasma viremia but also leads to very rapid disease progression within 12 to 16 weeks. In this model, passive transfer of high doses of neutralizing IgG (SHIVIG) prevents infection. Here, we show that at lower doses, SHIVIG reduces both plasma and peripheral blood mononuclear cell (PBMC)-associated viremia and mitigates pathogenesis in infected animals. Moreover, production of endogenous NAbs correlated with lower set-point viremia and 100% survival of infected animals. New SHIV models are needed to investigate whether passively transferred antibodies or antibodies elicited by vaccination that fall short of providing sterilizing immunity impact disease progression or influence immune responses. The 1-month-old rhesus macaque SHIV model of infection provides a new tool to investigate the effects of antibodies on viral replication and clearance, mechanisms of B cell maintenance, and the induction of adaptive immunity in disease progression.
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http://dx.doi.org/10.1128/JVI.00049-13DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3807376PMC
October 2013

Simplifying the synthesis of SIgA: combination of dIgA and rhSC using affinity chromatography.

Methods 2014 Jan 25;65(1):127-32. Epub 2013 Jun 25.

Department of Immunology and Microbial Science and IAVI Neutralizing Antibody Center, The Scripps Research Institute, La Jolla, CA, USA. Electronic address:

The mucosal epithelia together with adaptive immune responses, such as local production and secretion of dimeric and polymeric immunoglobulin A (IgA), are a crucial part of the first line of defense against invading pathogens. IgA is primarily secreted as SIgA and plays multiple roles in mucosal defense. The study of SIgA-mediated protection is an important area of research in mucosal immunity but an easy, fast and reproducible method to generate pathogen-specific SIgA in vitro has not been available. We report here a new method to produce SIgA by co-purification of dimeric IgA, containing J chain, and recombinant human SC expressed in CHO cells. We previously reported the generation, production and characterization of the human recombinant monoclonal antibody IgA2 b12. This antibody, derived from the variable regions of the neutralizing anti-HIV-1 mAb IgG1 b12, blocked viral attachment and uptake by epithelial cells in vitro. We used a cloned CHO cell line that expresses monomeric, dimeric and polymeric species of IgA2 b12 for large-scale production of dIgA2 b12. Subsequently, we generated a CHO cell line to express recombinant human secretory component (rhSC). Here, we combined dIgA2 b12 and CHO-expressed rhSC via column chromatography to produce SIgA2 b12 that remains fully intact upon elution with 0.1M citric acid, pH 3.0. We have performed biochemical analysis of the synthesized SIgA to confirm the species is of the expected size and retains the functional properties previously described for IgA2 b12. We show that SIgA2 b12 binds to the HIV-1 gp120 glycoprotein with similar apparent affinity to that of monomeric and dimeric forms of IgA2 b12 and neutralizes HIV-1 isolates with similar potency. An average yield of 6 mg of SIgA2 b12 was achieved from the combination of 20mg of purified dIgA2 b12 and 2L of rhSC-containing CHO cell supernatant. We conclude that synthesized production of stable SIgA can be generated by co-purification. This process introduces a simplified means of generating a variety of pathogen-specific SIgA antibodies for research and clinical applications.
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http://dx.doi.org/10.1016/j.ymeth.2013.06.022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3858571PMC
January 2014

A nonfucosylated variant of the anti-HIV-1 monoclonal antibody b12 has enhanced FcγRIIIa-mediated antiviral activity in vitro but does not improve protection against mucosal SHIV challenge in macaques.

J Virol 2012 Jun 28;86(11):6189-96. Epub 2012 Mar 28.

Department of Immunology and Microbial Science and IAVI Neutralizing Antibody Center, The Scripps Research Institute, La Jolla, California, USA.

Eliciting neutralizing antibodies is thought to be a key activity of a vaccine against human immunodeficiency virus (HIV). However, a number of studies have suggested that in addition to neutralization, interaction of IgG with Fc gamma receptors (FcγR) may play an important role in antibody-mediated protection. We have previously obtained evidence that the protective activity of the broadly neutralizing human IgG1 anti-HIV monoclonal antibody (MAb) b12 in macaques is diminished in the absence of FcγR binding capacity. To investigate antibody-dependent cellular cytotoxicity (ADCC) as a contributor to FcγR-associated protection, we developed a nonfucosylated variant of b12 (NFb12). We showed that, compared to fully fucosylated (referred to as wild-type in the text) b12, NFb12 had higher affinity for human and rhesus macaque FcγRIIIa and was more efficient in inhibiting viral replication and more effective in killing HIV-infected cells in an ADCC assay. Despite these more potent in vitro antiviral activities, NFb12 did not enhance protection in vivo against repeated low-dose vaginal challenge in the simian-human immunodeficiency virus (SHIV)/macaque model compared to wild-type b12. No difference in protection, viral load, or infection susceptibility was observed between animals given NFb12 and those given fully fucosylated b12, indicating that FcγR-mediated activities distinct from FcγRIIIa-mediated ADCC may be important in the observed protection against SHIV challenge.
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http://dx.doi.org/10.1128/JVI.00491-12DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3372207PMC
June 2012